DRAKE SCT4860 Manual de instruções - Página 5

Procurar online ou descarregar pdf Manual de instruções para Modulador DRAKE SCT4860. DRAKE SCT4860 15 páginas. Transcoder system

Imprimir página

General Description / Installation and Mounting

GENERAL DESCRIPTION

The R.L. Drake model SCT4860 is a professional quality,

modular, digital headend component providing QPSK or

8PSK input to QAM transmodulation and RF

upconversion functions in a single module. Up to ten

SCT4860 modules and a power supply module can be

accommodated in the RMT150 rack mounting tray,

occupying only a 2 unit (3.5") high rack space. The

SCT4860 can transcode DigiCipher II or DVB digital

satellite signals, included those with advanced turbo

satellite FEC modes, outputting QAM modulation.

The SCT4860 accepts L band RF inputs between 950

and 2150 MHz from the LNB at the satellite dish. The

transcoder demodulates the selected satellite QPSK or

8PSK signal. The forward error correction (FEC) imbed-

ded in the data stream is used to help retrieve an error

free digital transport stream containing the desired digital

programming multiplex.

If a fixed output clock rate has been selected, the null

packets in the transport stream are processed

INSTALLATION AND MOUNTING

Install the SCT4860 transcoders in the RMT150 rack

mounting frame. Slide each module into the tray so that

the "F" connector extends though the front panel hole, the

LED is properly aligned behind its front panel hole, and

the hook shaped projection on the bottom of the module

engages the rear of the mounting tray. Secure the

module with the supplied standard 1/2 inch "F" connector

mounting nut and nylon washer.

Similarly, mount the PS151 power supply in the RMT150

tray, making sure that the LCD display and control buttons

line up with their corresponding holes in the front panel,

and that the hook shaped projections on the rear of the

unit engage the rear of the mounting tray. Secure the

unit in place, with the supplied Philips head black

screws, from the front panel. Connect each SCT4860 to

the PS151 with the cable included with the SCT4860.

Each SCT4860 can connect to any one of the ten sockets

on the power supply. However, to minimize confusion, it

is suggested that the left most unit (as viewed from the

front panel) be connected to power supply socket

number 1, the second from the left to number 2, etc.

RS232 OUT

RS232 IN

+12

GND

FAN POWER

100 - 240 VAC

47 - 63 HZ, 125 W

L BAND INPUTS

RF OUTPUT

POWER

to provide the selected rate. When required, PCRs are

recalculated.

The transcoder then applies cable environment FEC to

this stream and remodulates using QAM modulation that

occupies a nominal 6 MHz wide cable channel slot. QAM

modes up through 1024QAM are supported.

The RF upconverter then upconverts the IF QAM signal to

the selected output channel - any standard EIA, IRC, or

HRC CATV channel or a broadcast off-air channel

frequency in the range of 54 to 860 MHz.

Bandpass flatness and phase noise are very closely

controlled in the SCT4860 to insure a high MER and S/N

ratio of the output signal. This insures that the transcoder

will not introduce a source of errors into the distribution

process. Because the MPEG2 transport stream informa-

tion is not modified by the transcoder, all encryption,

authorization, and program guide information is passed

on to the CATV set top box, unchanged.

Connect the LNB signal from the LNB splitter to each

SCT4860 module at the front panel connector. Connect

each SCT4860 RF output "F" connector on the rear of the

unit to the output combiner. Plug the cable from the front

panel fan module into the FAN POWER receptacle on the

rear of the power supply. Plug the line cord from the

PS151 into the AC power source. SCT4860s can be

mixed with SCT1860s, SCT2860s, or SCT3860s in the

same RMT150, using a common PS151 power supply.

When installing the RMT150 tray of transcoders, it is not

necessary to leave a vertical airspace between the

transcoder tray and other equipment unless that other

equipment specifies that a space should be left open.

The air flow through the transcoders and power supply

has been designed to allow immediate adjacent

mounting of multiple RMT150 trays with SCT4860

transcoders and PS151 power supplies installed. Of

course, air spaces may be left in between RMT150s if

desired.

RF OUTPUT

POWER

DRAKE TRANSCODER SYSTEM

1.1

12.45 dB

UNIT

SELECT

ENTER

RF OUTPUT

POWER